1. Field of the Invention
The present invention relates to a display device, and more particularly, to an image projector. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for selecting one of image brightness and color definition through a single projector, when viewing a projected image, thereby projecting the image in accordance with the user's preference.
2. Discussion of the Related Art
As image projection devices, also known as the projector, are being extensively introduced and provided, diverse types of product are being developed and sold on the market. Such image projection devices are under development for a structure focusing on the brightness of the projection and the compact size and light weight of the device.
An optical part of a general image projection device includes a lamp as a light source, an illuminating part focusing the light emitted from the lamp, an image display device representing the focused light into an image, and a projecting part enlarging the image displayed on the image display device and projecting the enlarged image onto a screen.
In the present technology, high pressure mercury lamps are most widely used as the lamp of the image projection device, and liquid crystal displays (LCDs) and digital micromirror devices (DMDs) are most widely used as the image display device of the projector. Additionally, depending upon the number of image display devices used, the image projection device can be categorized as a single-chip projector, a two (2)-chip projector, and a three (3)-chip projector.
As the recent trend introduces projectors of compact size, light weight, and low cost, single-chip optical parts using only a single image display device is generally used.
The single-chip image projection device includes a projector type mounting color filters of red, green, and blue, a projector type externally separating red, green, and blue light rays and simultaneously illuminating the separated light rays to the image display device, and a projector type externally and sequentially illuminating red, green, and blue light rays onto the image display device with a time interval. Herein, when using the projector type externally and sequentially illuminating red, green, and blue light rays onto the image display device with a time interval, the response speed of the image projection device is required to be three times faster than that of the three (3)-chip image projection device. In the recent technology, the digital micromirror device (DMD) most satisfies such requirements.
A color separating device is formed in order to illuminate separated light rays onto the image display device. When using the projector for presentations focusing on the brightness of the screen is important, a four-sectioned color wheel should be used. On the other hand, when using the projector for viewing video images emphasizing various colors, a three-sectioned color wheel should be used. The same principle applies to a color drum.
As described above, the single-chip DMD projector is disadvantageous in that an adequate color separating device emphasizing either one of brightness or color representation should be selected, depending upon whether the product is focused on the brightness of the screen or the color picture quality of the image. However, the single-chip projector used in the current technology cannot satisfy the user environment of the recent multimedia trend requiring both characteristics (i.e., brightness and color representation).